This paper studies the potential application of ventilation systems with thermal energy storage (TES) using phase change materials (PCMs) for space cooling in air conditioned buildings during the summer. A south-facing middle office room located in Beijing, China is considered for study. To simulate the indoor thermal environment and energy consumption of the room, a dynamic computational model which consists of a building thermal model, a heat transfer model of a TES unit and the performance curve of an air conditioner (AC) is built and validated. The time lag to switch on AC, the cooling energy provided by AC, PCMs and structure elements, the runtime of AC and fan, and the overall electricity energy consumption of the TES system are calculated and compared to a base case without night ventilation (NV) and a case with conventional NV system. The results indicate that the higher the indoor temperature set point, the higher the cooling energy contributions of PCMs and structure elements and therefore the higher the potential application of the TES system. The electricity energy saving ratio (ESR) by using the TES system over the base case is found to be 16.9%-50.8%, while that against the conventional NV system is 9.2%-33.6%. (C) 2019 Elsevier Ltd. All rights reserved.